Pressure relief valve

ABSTRACT

A pressure relief valve has a single piece outer body or housing with an inlet and an outlet formed therein communicating with a chamber formed internally of the housing; a moveable valving member situated within the chamber is generally contained within a removable valve guide and is resiliently urged toward a closed position against the inlet by a spring also contained within the valve guide; and a manually actuated lever is operatively connected to the valving member through a valve stem member which is connected to the valving member in a manner providing for a lost motion connection therebetween.

[ 1 Sept. 11, 1973 1 PRESSURE RELIEF VALVE [76] Inventor: James D. Orr,6330 E. Surrey,

Birmingham, Mich. 48010 22 Filed: Feb. 10, 1972 21 Appl. No.: 225,140

Powell ,1 137/475 Chapman 137/469 X Primary Examiner-Harold W. WeakleyAttorney-David A. Maxon 571 ABSTRACT A pressure relief valve has asingle piece outer body or housing with an inlet'and an outlet formedtherein communicating with a chamber formed internally of the housing; amoveable valving member situated within the chamber is generallycontained within a removable valve guide and is resiliently urged towarda closed position against the inlet by a spring also contained withinthe valve guide; and a manually actuated lever is operatively connectedto the valving member through a valve stem member which is connected tothe valving member in a manner providing for a lost motion connectiontherebetween.

8 Claims, 7 Drawing Figures PATENTEDSIZPI 1 ms BACKGROUND OF THEINVENTION Various forms of pressure relief valve assemblies haveheretofore been proposed by the prior art. However, such prior art valveassemblies, although-usually found generally acceptable in theiroperation, have, nevertheless, been of a configuration requiringadditional manufacturing operations as well as generally costlymachining operations. Further, heretofore, the prior art valves, inorder to permit assembly of the various elements comprising suchassemblies, required that the outer valve housings be made in at leasttwo pieces which, in turn, had to be secured to each other during finalassembly. I

Accordingly the invention as herein disclosed and claimed is primarilydirected to the solution of the above as well as other related problemsand disadvantages of the prior art.

FIG. 4 is an enlarged view ol'a fragmentary portion of the structure ofFIG. 1;

FIG. 5 is an enlarged view of a different fragmentary portion of thestructure of FIG. 1;

FIG. 6 is a fragmentary portion of a modification of the invention; and

SUMMARY OF THE INVENTION adapted to be effective for closing saiddischarge orifice means, said valving means comprising a valving memberhaving a valving surface generally juxtaposed to said discharge orificemeans, said valving surface including a contoured deflecting surfaceportion progressively increasingly exposed to said pressurized fluidwithin said inlet means as said valving member is progressively movedaway from said discharge orifice means, said contoured deflectingsurface portion being effective upon so being moved away from saiddischarge orifice means to deflect and change the path of travel of saidpressurized fluid flowing from said inlet means and into said chamberthereby causing said valving member to experience a reaction force inopposition to the force of said resilient means tending to bias saidvalving member closed against said discharge orifice means, and valveguide means separate from said valve body for operatively engaging andguiding said valving as said valving member moves with respect to saiddischarge orifice means.

Various generaland specific objects and advantages of the invention willbecome apparent when reference is made to the following detaileddescription of the invention considered in conjunction with theaccompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein for purposes ofclarity certain elements and/or details may be omitted from one or moreviews;

FIG. 1 is a generally longitudinal or axial crosssectional view of avalve assembly constructed in accordance with the teachings of theinvention;

FIG. 2 is a view similar to that of FIG. 1 but illustrating a secondembodiment of the invention;

FIG. 3 is a view similar to that of FIG. 1 but illustrating a thirdembodiment of the invention;

fication of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detailto the drawings, FIG.

1 illustrates a valve assembly 10 having a main outer body or housing 12with integrally formed projecting body portions 14, 16 and 18. Bodyportion 14 is preferably externally threaded, as at 20, and has aconduit or nozzle section 22 formed therein. One end of conduit 22 isadapted for communication with a related source 24 of pressurized fluid(such as, for example, a steam boiler or generator) while the other endof conduit 22, formed to be open, is adapted for communication with amain chamber 26 formed within housing 12. The degree of communicationexperienced between conduit 22 and chamber 26is determined by a moveablevalving member 28 normally resiliently urged to a closed position (asshown in FIG. 1) by suitable cooperating resilient means such as acoiled compression spring 30.

Body portion 16 has a conduit 32 formed therethrough including apreferably internally threaded portion 34. The inner end of conduit 32is in continual communcation with chamber 26 while the other end ofconduit 32 is adapted and intended for'communication with a related area36 of relatively low pressure.

Formed internally of housing 12 is a generally radially inwardlydirected flange-like portion 38 defininga generally cylindrical aperture40 along with an annular seatingsurface 42. A removable but preferablytightly engaging generally tubular guide member 44 is received throughaperture 40 in a manner as to have an integrally formed generallyradially outwardly radiating flange portion 46 abutingly engaging theabutment surface 42. v i

Body portion 18 is provided with an internally threaded section 48 whichthreadably engages an exter nally threaded portion 50 of a capping-likeend member 52. As illustrated, the end member 52 may be provided with aplurality of conduit portions 54 formed therethrough for communicationwith, for example, the ambient atmosphere, and an additional clearancetype passageway 56 for the passage therethrough of a generallycylindrical valve stem 58. As can be seen a generally annular spring 60of wavy-like configuration is contained generally between the inner endof plug member 52 and flange 46 of valve guide 44. In threading cappingmember 52 inwardly, the end member52 tends to further compress the waveportions of the spring 60 and in so doing applies a resilient forceagainst flange 46 thereby holding it against the abutment or seatingsurface 42.

One end of compression spring 30 is seated against end capping member 52whilethe other end of spring 30 is seated against a moveable spring seator perch 62, which may be of a generally inverted cup-shapedconfiguration, received generally about the stem 58 but prevented fromdownward movement relative to stem 58 as by an abutment in the form of across-pin 64 received in a cooperating aperture formed through the valvestem 58. As should be apparent, the more end member 52 is threadedinwardly of housing portion 18 the more will spring 30 undergocompression and therefore the greater will be the resilient forceagainst valve member 28 tending to hold valve member 28 closed againstinlet conduit 22.

The lower end of valve stem 58 is operatively connected to valve member28 in a manner to be hereinafter more fully described, while the upperend 66 is operatively pivotally connected to a manually actuated lever68. Lever 68, when viewed in' transverse crosssection, may be of aconfiguration including parallel downwardly depending wall portions, oneof which is shown at 70, which are joined as by a longitudinallyextending bight portion 72. The upper end 66 of stem 58 may, in turn, bepositioned between such parallel wall portions (typically illustrated at70) and pivotally connected thereto as by a pivot pin 74 operativelyengaging opposed parallel wall portions of lever 68 and passing througha receiving passageway 76 formed in stem 58. Each of the lever wallportions is preferably provided with a cam surface, typicallyillustrated at 78, which is held in engagement with the outer surface ofend cap member 52. The cam surface 78 is, of course, functionallyeccentric with respect to privot pin 74. Therefore, as lever 68 isrotated generally clockwise about the axis of pivot pin 74, stem 58 iscorrespondingly moved upwardly thereby lifting valve member 28 againstthe resilient resistance of spring 30 and manually completingcommunication between chamber 26 and inlet conduit 22.

FIG. 5, an enlarged fragmentary portion of FIG. 1, better illustratesthe means and manner for operatively connecting the lower end of stem 58to the valve member 28. In considering each of FIGS. 1, 4 and 5, it canbe seen that valving member 28 comprises a disc-like main body 78 havingan integrally formed generally cylindrical up-standing body portion 80which is externally threaded as at 82 and internally threaded as at 84.A chamber like opening or recess 86 extends further into the valvingmember 28 and may preferably terminate as in a generally spherical endsurface 88.

The valve stem 58 is provided with a necked-down extension 90 whichcarries, near the end thereof, an externally threaded portion 92. Theextension 90 may ultimately terminate in an abutment surface such as agenerally spherical end surface 94.

As best seen in FIG. 5, an insert 96, commonly referred to as aheli-coil insert, is threadably engaged within the internally threadedportion 84 of valving member 28. A heli-coil may be described as agenerally cylindrically extending helical body having an externallyformed thread configuration, as at 98, formed thereon and an internallyformed thread configuration, as at 100, also formed thereon. Suchheli-coil inserts are, for example, typically illustrated in theI-Ieli-Coil Corporation catalog Bulletin 900, copyrighted by theHeli-Coil Corporation in 1970.

The internally threaded portion 84 and heli-coil insert 96 are selectedof such dimensions as to enable the externally threaded portion 92 ofstem 58 to be threadably engageable with the interior thread formation100' of insert 96. Accordingly, the stem 58 may rotate causing threadedportion 92 to threadably engage and ultimately pass through theheli-coil insert 96 assuming a position as generally depicted in any ofFIGS. 1, 2, 3 or wherein the threaded portion 92 is generally looselyconfined within chamber 86 but prevented from withdrawal therefrom byvirtue of the heli-coil insert 96. This, in effect, defines a lostmotion connecting means as between the stem58 and valving member 28.

For sake of clarity, the heli-coil inserts in FIGS. 1, 2

and 3 are shown in cross-section but are purposely not cross-hatched.

Referring now in greater detail to FIGS. 1 and 4, it can be seen thatthe interior of valve housing 12 is formed as to define a generallyfrusto-conical portion having a generally tapered outer surface 102which terminates, at its upper end, in a generally transverse pla narsurface 104. The planar surface 104 is interrupted by an orifice 106defining the discharge orifice of conduit 22 and an annular recess orgroove 108 which includes an annular end surface 110 and opposedcircular wall surfaces 112 and 114. The groove 108, in effect, definesannular lands or surfaces 116 and 118m radially opposite sides thereof.

The valving member 28 is preferably provided with a downwardly directedvalving surface 120 which has formed therein a first annular groove orrecess 122 comprised generally of an annular end surface 124 and opposedcircular walls 126 and 128. A second annular groove 130 is defined as bya centrally positioned downwardly depending generally sphericalprotuberance or extension 132 and a circular wall 134 joined to the baseof the extension 132 as by an annular end surface 136. As can be seen,annular groove 122 and 130 also serve to define annular lands orsurfaces 138 and 140.

In FIG. 4, the valving member 28 is shown in an opened position (withthe degree of actual opening possibly being to some degree exaggeratedin order to more clearly illustrate the various elements and detailsthereof. However, as shown in FIG. 1, when the valving member 28 is inits closed position, ideally annular surface 140 of valving member 28 isjuxtaposed to and held in abutting engagement with annular surface 118of the frusto-conical portion 101 in a manner whereby circular walll34forms a continuous extension of discharge orifice 106 and wherebycircular wall surfaces 128 and 138 define a continuous cylindricalsurface. At this time, as is also best seen in FIG. 1, annular landsurface 116 is disposed as to be generally opposed to recess 122 andsituated as to be radially between circular walls 126 and 128.

OPERATION Let it be assumed that apparatus 24 is a steam generatorsupplying steam to some related consuming device as via conduit means 25and that the valve assembly 10 is operatively connected thereto as byconduit means The pre-load force of spring 30 serves to hold valvingmember 28 closed against the discharge orifice 106 thereby precludingthe flow of suchpressurized fluid through inlet conduit means 22 andinto chamber 26. The valving member continues to be held in its closedposition until such time as the pressure of the steam in conduit 22increases to such a magnitude resulting in a pressure differentialacross the valving member 28 sufficient to overcome the pre-load forceof spring 30. When the pressure of such pressurized fluid attains such amagnitude, valving member 28 starts to move upwardly and away from thedischarge orifice 106. The instant that valving member 28 so starts tomove, the

pressurized fluid starts to pass between the very slight space betweenjuxtaposed lands or surfaces 118 and 140. As the pressurized fluidcontinues its generally radially outward travel, its otherwise smoothflow is somewhat interrupted by the lower annular groove 108 and upperannular groove 122, also an annular nozzle is formed between surfaces116 and 124 providing a throttling on the escape of fluids. The effectof such grooves 108 and 122 is to create a degree of turbulence in theflow of the escaping pressurized fluid as well as to in effect reducethe velocity of flow of fluid relative to the radial extent of thesurfaces 104 and 120.These grooves cooperate to form a restrictioncreating pressure on a larger area of disc 28. This is achieved bynozzle throttling through an annular area creating statis pressure overdisc 28. Both of such effects result in an increase in the magnitude ofthe static pressure of the fluid against the valving member 28 as wellas exposing a greater effective area of the lower surface 120, ofvalving member 28, to be acted against by such pressurized fluid.

Consequently, as soon as the pre-load of spring 30 is exceeded, valvemember 28 starts to move upwardly; and as soon as valve member 28 startsto move upwardly the effective area of the valve member 28 is increasedas well as the magnitude of the static pressure of the fluid flowingpast valve 28 thereby creating an increased reaction force against valve28 moving the valve 28 still further away from the discharge orifice106.

As valving member 28 so continues to move upwardly it attains a positionas generally depicted in FIG. 4 at which time the force of the furthercompressed spring 30 is balanced by the force of the pressurized fluidthe path of which is generally depicted by the broad arrows. As can beseen, the escaping pressurized fluid is caused to effectivelystrike thelower valving surface 120 and then change direction and flow downwardlythrough the annular space defined between the lower open end of thevalve guide 44 and the tapered surface 102 of the frusto-conical portion101. The en- I ergy expended in causing the escaping pressurized fluid.

to reverse its direction is realized as a reaction force against thelower surface 120to first raise higher and then tending to hold thevalve member 28 open.

The cracking pressure (that pressure at which valve 28 starts to moveupwardly away from the discharge or-' ifice 106) may be readily adjustedby means of the capmember or adjusting nut 52. That is, in order toassure closure of valve 28 until some higher magnitude of pressure isattained by the pressurized fluid, all that needs to be done is tothreadably rotate the nut 52 inwardly thereby further compressing spring30 and correspondingly increasing the pre-load force of spring 30 onvalve 28. The converse is, of course, also true. The

wave spring 60 is capable of sufficient deflection to enblowdown do notvary substantially, only one such spring 30 having a specified springrate and size need be used. However, in the second and third embodimentsof the invention, to be discussed more fully hereinafter, different sizesprings have: different spring constants for the spring member 30 arerecommended upon specification of the threshold of pressure foractuation and blowdown of the valve.

SECOND EMBODIMENT OF THE INVENTION FIG. 2 illustrates a secondembodiment of the invention. All elements in FIG. 2 which are like orsimilar to those of FIGS. 1, 4 and 5 are identified with like refer encenumerals with a suffix a.

In the valve assembly 10a, the generally transverse 'wall portion 38a isprovided with an internally threaded aperture 142 which threadablyengagees an externally threaded portion 144 carried by the tubular valvemember guide 44a. The upper end of guide 440 is provided with aplurality of circumferentially arranged re ce'sses or flated portionswhich, as illustrated, coact with an end 143 of a locking screw 146threadably carried by housing 12a. The purpose of the threaded portions142 and 144 is to enable relative rotation and axial movement of guide44a in order to selectively position the lower open end of guide 44a ina desired relationship to the fru'sto-conical portion 101a.

The valve member guide 44a is thus axially adjustable and thus operableto control the pressure threshold at which the valve closes again. Thus,a Vernier-like precision axial setting of the guide is achievedwhichpermits a Vernier-like precision adjustment of the valve blowdownpressure threshold.

The valving member 280 is preferably provided with an elongatedcylindrical skirt portion 148 and a plurality of circumferentiallyextending grooves 150 axially enabling any pressurizedfluid, which mayleak between the valve and guide, to undergo a reduction in the velocityof such leakage flow as it successively reaches each of such spacedgrooves 150. i

The means and manner for securing the lower end of stem 58a to thevalving member 280 is the same as that disclosed in FIG. 5 while theconfigurations, grooves and surfaces of transverse surface 104a and thevalving surface 120a are respectively like those of 104 and 120 of FIG.4. I

The operation of valve assembly 10a is like that as described in detailwith reference to FIGS. 1, 4 and 5.

THIRD EMBODIMENT OF THE INVENTION FIG. 3 illustrates a third embodimentof the invention. All elements in FIG. 3 which are like or similar toeither FIGS. 1, 2, 3, or 5 are identified with like reference numeralsprovided with a suffix b.

In the embodiment of FIG. 3, a generally cup-shaped member 28a, an innerperipheral portion of a rolling diaphragm 156 which has its other endsecured to the outer cylindrical surface of tubular valve guide 44b. Anysuitable means such as a ring-like band 158 generally press-fitted overthe outer end of the diaphragm 156 may be employed for anchoring thediaphragm to the guide 44b. In one successful embodiment of theinvention, the diaphragm 156 was comprised of a Buna N reinforced nylonsuch as that marketed under the tradename Bellofram, sold by theBellofram Corporation and disclosed in U.S. Pat. No. 2,849,026.

The primary purpose of providing such a diaphragm 156 is to define apositive seal in order to prevent the leakage of liquid fluids past thevalving member and into the upper interior of valve guide 44a. Thisbecomes of special importance where the valve assembly is to be incombination with, for example, water heaters or hot water pressurevessels.

The means and manner for securing the lower end of stem 58b to thevalving member 28b is the same as disclosed in FIG. while theconfigurations, grooves and surfaces of transverse surface l04b and thevalving surface 120b are respectively like those of 104 and 120 of FIG.4.

The operation of valve assembly b is like that as disclosed in detailwith reference to FIGS. 1, 4 and 5 except that as the valving member 28bmoves upwardly or downwardly the intermediate body portion of thediaphragm rolls upwardly or downwardly generally upon itself therebycontinually effecting a positive seal as between the valve guide 44b andvalving member 28b.

CONCLUSION It should be apparent that the invention as herein disclosedprovides a multitude of important benefits and improvements over theprior art. 7

For example, with the invention it is possible to make the outer valvehousing as a one piece structure. Although the invention is not solimited, nevertheless, the outer valve housings may be cast of anysuitable material such as bronze and later machined as required. Also,it is contemplated that one standard configuration of such outer valvehousing could be cast which would be employable in either of the threeembodiments disclosed. For example, it would be possible to cast such anouter housing to meet the requirements of housing 12a and then,depending on how the housing were to be employed, drill and tap forscrew 146 (or leave blank) and either drill and tap threads 142 (FIG. 2)or drill and ream the aperture 40 (FIG. 1).

In various successful embodiments of the invention, the valve guide,such as at 44, was made of brass. However, other suitable materials may,of course, be employed. All of the valve guides are a distinctimprovement over the prior art in many ways. For example, each is easilyremoved as by withdrawal through the threaded aperture containing thenut 52, 52a or 52b. Further, each of such valve guides is axiallyadjustable with respect to, for example, the tapered surface 102, 102aor l02b. In the embodiment of FIGS. 1 and 3, such axial adjustment maybe easily achieved as by the placement of a suitable shim 160 betweenthe valve guide flange and the abutment surface as typically illustratedin FIG. 6. Such a feature of axial adjustability is important becausethe proximity of the open end of the valve guide to the tapered surface102 will determine both the angle of deflection of the escapingpressurizedfluid as well as the effective flow are therebetween. Asshould be apparent, the lesser the effective flow area between the endof the valve guide and the tapered surface 102 the greater will be therestriction to flow therethrough.

Accordingly, each of the valve guides of the invention can easily beaxially adjusted in order to attain the degree of valve sensitivitydesired or required, as, for example, in those instances where valveblow down is held to close limits relative to relief pressure settings.

Annular chamber 108 (as well as 108a and 108b) and annular chamber 122(as well as chambers 122a and 122b) functionally define what is oftenreferred to as huddling chambers. However, such huddling chambers asherein disclosed are unlike the prior art in that the open ends of suchchambers are located on what might be considered generally as a planenormal to axis of the discharge orifice 106 and at a relative axialposition generally coplanar with such discharge orifice. Suchconfigurations of huddling chambers as herein disclosed and claimed havebeen found to be extremely effective for creating an additionalincreased force tending to open the valving member immediately uponinitial opening movement of the valve member.

As has already been stated, the pressure setting of the valve assembliesof the invention can be made merely by rotation of the nut, as 52,without in any way disturbing the functioning of any other component.

The use of the heli'coil type insert, as shown at 96, provides variousbenefits. First, valve assemblies of the prior art employed an undercutform of chamber into which the end of the stem was introduced. Asuitable clip was then employed to loosely retain such stem end withinthe undercut chamber.

The employment of a heli-coil type insert eliminates the need ofmachining such an undercut chamber,

. which is an expensive machining operation. The invention obviates thenecessity of such an undercut chamber by requiring a simple cheapertapping operation to form threads 84 which will accommodate theheli-coil type insert 96 which serves to retain the end of the stem 58within the chamber 86.

Another benefit of the heli-coil type insert 96 is its Iaxial'adjustability. For example, in all valve assemblies of the typedisclosed, it is necessary to provide a degree of lostmotion between theend of the stem 58 and valving member 28 in order to insure against thepossibility that valving member 28 will accidentally be lifted off itsseat when the manually actuated lever 68 is in the position showninFIG. 1. Accordingly, the use of an adjustable abutment, such as 96,enables the heli-coil type insert 96 to be variably axially positionedwith respect to the threaded portion 92 of stem 58 in order to: (a)assure the attainment of the required degree of lost motion therebetweenbut (b) at the same time assuring that the degree of lost motion is notso great as to preclude the lifting of the valve member 28 by actuationof the lever 68. This, of course, means that manufacturing tolerancesfor the lever 68, stem 58 and the valving member 28 may, to some extent,be made more liberal and therefore reduce the related manufacturingcosts.

Although in the preferred embodiment of the invention: the outer housing12 and valving member 28 are made of bronze; the valve guide 44 is madeof brass; the spring 30, spring cup 62 and lever 68 are made of steel;and the nut 52 is made of cast iron; such components may, of course, bemade of any material suitable to the intended use of such valveassemblies.

Further various modifications of the invention are contemplated amongwhich is the provision of an annular resilient seal 162 carried as bythe valving member 28 (or any of the other corresponding valvingmembers) within a suitable recess 164 as depicted in FIG. 7. When thevalve 28 is in its closed position, the seal 162, which may be of anO-ring configuration, is par-' tially compressed while when the valve 28is opened, the seal 162 would at least slightly extend beyond the faceof the valving member 28.

The embodiment of the invention shown in FIG. 1 is recommended for useas a safety valve for steam heat boilers. The embodiment illustrated inFIG. 2 is recom mended for a valve for a process steam boiler forchemical, petroleum'or other industrial processing. The embodimentillustrated in FIG. 3 is recommended for a water relief valve for hotwater heaters and hot water pressure vessels. Each of these threedifferent applications have different pressure threshold requirementsfor actuation. For example, safety valves for steam heat boilers usuallyrequire an actuation pressure for relief of 15 psi and have no blowdownrequirement. Valves for a process steam boiler for chemical, petroleumor other industrial processing may have pressure relief thresholdrequirements, depending on particular use, of anywhere from 5 to 250psi, and all usually require a blowdown actuation at 4 percent less thanthe relief actuation threshold pressure. Water relief valves for hotwater heaters and hot water pressure vessels usually have no blowdownrequirements but must be water tight with a resilient seating.

Despite the fact that different embodiments of the invention discussedabove have different actuation requirements and applications, it can beappreciated from the foregoing description of these embodiments that asubstantial number of components of each of these valves are similar.Thus, a substantial elimination of complication and cost in manufactureand maintenance of these valves is achieved.

Although only selected preferred embodiments of the invention have beendisclosed and described, it is apparent that various other embodimentsand modifications of the invention are possible within the scope of theappended claims.

I claim:

1. A fluid pressure relief valve assembly comprising a valve housing,inlet means formed in said valve housing adapted for communication witha related source of fluid under pressure, chamber means formed withinsaid valve housing, outlet means formed in said valve housing andcommunicating with said chamber means, said inlet means includingdischarge orifice means leading to said chamber means, valving meansadapted to be effective for at times closing said discharge orificemeans so as to terminate communication between said discharge orificemeans and said chamber means, first resilient means for normally biasingsaid valving means to a closed position against said discharge orificemeans, said valving means comprising a valving member having a valvingsurface generally juxtaposed to said discharge orifice means,sleeve-like valve guide means separate from and slidably received bysaid valve housing for operatively containing and guiding said valvingmember as said valving member moves with respect to said dischargeorifice means, abutment ill means carried by said valve housinginternally thereof for operatively engaging a portion of saidsleeve-like valve guide means to thereby preclude further relative axialmovement of said sleeve-like valve guide means, second resilient meansfor normally biasing said sleevelike valve guide means into operativeabutting engagement with said abutment means, an access opening formedin said valve housing, said access opening being so located as to begenerally on one side of said chamber means and opposed to saiddischarge orifice means, said access opening being of a dimensionpermitting the passage therethrough of said sleeve-like valve guidemeans, and adjustably positioned closure means situated generally withinand operatively engaging said access opening, said closure means beingeffective to simultaneously adjustably determine a pre-load force insaid first and second resilient means in order to thereby resilientlyhold said valving member closed against said discharge orifice meansuntil said fluid under pressure attains a predetermined magnitude ofpressure and to resiliently hold said sleeve-like valve guide means inoperative abutting engagement with said abutment means.

2. A fluid pressure relief valve assembly according to claim 1, whereinsaid valve housing comprises an internally formed generallyfrusto-conical housing portion defining a portion of the wall surface ofsaid chamber means and effectively circumscribing said discharge orificemeans, said frusto-conical housing portion includ ing a generallytapered annular surface the axis of which is substantially parallel tothe axis of said discharge orifice means, and wherein said sleeve-likevalve guide means comprises a tubular member open at either end, saidtubular member being axially posi tioned as to have one of said openendsin relatively close proximity to said tapered annular surface as todefine therebetween an annular passageway for the flow of said fluidunder pressure whenever said valving member has been moved away fromsaid discharge orifice means.

3. A fluid pressure relief valve assembly according to claim 1,including manually actuated means for manually moving said valvingmember away from said discharge orifice means, said manually actuatedmeans comprising a cam-like lever situated externally of said valvehousing and continually resiliently urged by said first resilient meansinto operative abutting engagement against said closure means, and avalve stem member passing through said closure means and connected atone end to said lever and connected atflan other end to said valvemember. i

4. A fluid pressure relief valve assembly according to claim 1,including manually actuated means for manually moving said valvingmember away from saiddischarge orifice means, said manually actuatedmeans comprising a valve stem having a first portion adapted for manualactuation and a second portion operatively connected to said valvingmember by means of lost motion connecting means, said lost'motionconnecting means comprising a first threaded portion formed generally atan end of said valve stem, a second threaded portion formed on saidvalving member, and a threadably positionable abutment member havingthird and fourth threaded portions thereon, said third threaded portionbeing adapted for threadable engagement with said second threadedportion forrnedon said valving member, and said fourth threaded portionbeing effecsaid unthreaded section of said valve stem freely extendingthrough said fourth threaded portion.

5. A fluid pressure relief valve assembly according to claim 1,including diaphragm means having an outer peripheral portion secured tosaid sleeve-like valve guide means and an inner peripheral portionsecured to said valving member.

6. A fluid pressure relief valve assembly according to claim 5, whereinsaid sleeve-like valve guide means comprises an open-ended tubularmember, wherein said valving member is contained generally within saidtubular member, and wherein said diaphragm "means comprises a rollingdiaphragm sealing member, said rolling diaphragm being so positioned asto have the rolling portion thereof generally between said valvingmember and said tubular member.

7. A fluid pressure relief valve assembly according to claim 1,including an annular resilient seal carried by said valving member, saidresilient seal being so positioned as to circumscribe said dischargeorifice means whenever said valving member is closed against saiddischarge orifice means.

8. A fluid pressure relief valve assembly according to claim 1 whereinsaid valving means comprises an elongated valve stem member looselyconnected at one end to said valving member and having an other endextending through said closure means, spring retainer means carried bysaid stem member and effective for engaging said first spring means soas to have the resilient force of said first spring means transmittedthrough said. spring retainer means and said stem member and finallyinto said valving member, said spring retainer means being of cup-likeconfiguration including a cupbottom wall and integrally formed annularside wall terminating in a radially outwardly directed flange forengaging said first spring means, said cup-bottom wall having anaperture formed therein substantially centrally thereof for slidablyreceiving said valve stem therethrough, and said spring retainer meansbeing so positioned as to have said cup-bottom wall disposed closer tosaid closure means while said radially outwardly directed flange'isdisposed closer to said valving member.

1. A fluid pressure relief valve assembly comprising a valve housing, inlet means formed in said valve housing adapted for communication with a related source of fluid under pressure, chamber means formed within said valve housing, outlet means formed in said valve housing and communicating with said chamber means, said inlet means including discharge orifice means leading to said chamber means, valving means adapted to be effective for at times closing said discharge orifice means so as to terminate communication between said discharge orifice means and said chamber means, first resilient means for normally biasing said valving means to a closed position against said discharge orifice means, said valving means comprising a valving member having a valving surface generally juxtaposed to said discharge orifice means, sleeve-like valve guide means separate from and slidably received by said valve housing for operatively containing and guiding said valving member as said valving member moves with respect to said discharge orifice means, abutment means carried by said valve housing internaLly thereof for operatively engaging a portion of said sleeve-like valve guide means to thereby preclude further relative axial movement of said sleeve-like valve guide means, second resilient means for normally biasing said sleeve-like valve guide means into operative abutting engagement with said abutment means, an access opening formed in said valve housing, said access opening being so located as to be generally on one side of said chamber means and opposed to said discharge orifice means, said access opening being of a dimension permitting the passage therethrough of said sleeve-like valve guide means, and adjustably positioned closure means situated generally within and operatively engaging said access opening, said closure means being effective to simultaneously adjustably determine a pre-load force in said first and second resilient means in order to thereby resiliently hold said valving member closed against said discharge orifice means until said fluid under pressure attains a predetermined magnitude of pressure and to resiliently hold said sleeve-like valve guide means in operative abutting engagement with said abutment means.
 2. A fluid pressure relief valve assembly according to claim 1, wherein said valve housing comprises an internally formed generally frusto-conical housing portion defining a portion of the wall surface of said chamber means and effectively circumscribing said discharge orifice means, said frusto-conical housing portion including a generally tapered annular surface the axis of which is substantially parallel to the axis of said discharge orifice means, and wherein said sleeve-like valve guide means comprises a tubular member open at either end, said tubular member being axially positioned as to have one of said open ends in relatively close proximity to said tapered annular surface as to define therebetween an annular passageway for the flow of said fluid under pressure whenever said valving member has been moved away from said discharge orifice means.
 3. A fluid pressure relief valve assembly according to claim 1, including manually actuated means for manually moving said valving member away from said discharge orifice means, said manually actuated means comprising a cam-like lever situated externally of said valve housing and continually resiliently urged by said first resilient means into operative abutting engagement against said closure means, and a valve stem member passing through said closure means and connected at one end to said lever and connected at an other end to said valve member.
 4. A fluid pressure relief valve assembly according to claim 1, including manually actuated means for manually moving said valving member away from said discharge orifice means, said manually actuated means comprising a valve stem having a first portion adapted for manual actuation and a second portion operatively connected to said valving member by means of lost motion connecting means, said lost motion connecting means comprising a first threaded portion formed generally at an end of said valve stem, a second threaded portion formed on said valving member, and a threadably positionable abutment member having third and fourth threaded portions thereon, said third threaded portion being adapted for threadable engagement with said second threaded portion formed on said valving member, and said fourth threaded portion being effective for threadably engaging said first threaded portion in order to permit said first threaded portion to be threadably passed through said fourth threaded portion thereby leaving an unthreaded section of said valve stem freely extending axially through said fourth threaded portion, said threadably positionable abutment member being effective for relative axial adjustment through threadable rotation so as to thereby adjustably determine the position at which said first threaded portion will abut thereagainst when said first threaded portion is moved axially thereto and thereby limit the relative movement of said valve stem due to said unthreaded section of said valve stem freely extending through said fourth threaded portion.
 5. A fluid pressure relief valve assembly according to claim 1, including diaphragm means having an outer peripheral portion secured to said sleeve-like valve guide means and an inner peripheral portion secured to said valving member.
 6. A fluid pressure relief valve assembly according to claim 5, wherein said sleeve-like valve guide means comprises an open-ended tubular member, wherein said valving member is contained generally within said tubular member, and wherein said diaphragm means comprises a rolling diaphragm sealing member, said rolling diaphragm being so positioned as to have the rolling portion thereof generally between said valving member and said tubular member.
 7. A fluid pressure relief valve assembly according to claim 1, including an annular resilient seal carried by said valving member, said resilient seal being so positioned as to circumscribe said discharge orifice means whenever said valving member is closed against said discharge orifice means.
 8. A fluid pressure relief valve assembly according to claim 1 wherein said valving means comprises an elongated valve stem member loosely connected at one end to said valving member and having an other end extending through said closure means, spring retainer means carried by said stem member and effective for engaging said first spring means so as to have the resilient force of said first spring means transmitted through said spring retainer means and said stem member and finally into said valving member, said spring retainer means being of cup-like configuration including a cup-bottom wall and integrally formed annular side wall terminating in a radially outwardly directed flange for engaging said first spring means, said cup-bottom wall having an aperture formed therein substantially centrally thereof for slidably receiving said valve stem therethrough, and said spring retainer means being so positioned as to have said cup-bottom wall disposed closer to said closure means while said radially outwardly directed flange is disposed closer to said valving member. 